A 2004 satellite image provided by DigitalGlobe and the Institute for Science and International Security shows the military complex at Parchin, Iran, about 19 miles southeast of Tehran.

By Andrea Mitchell, NBC News

A senior administration official told NBC on Saturday that there have been back-channel talks between the U.S. and Iran about meeting bilaterally on the Iranians’ nuclear program – but that no meeting has been agreed to.

Expanding on a statement issued by the White House after The New York Times reported that there was an agreement, the official says that the backchannel talks have been done in full consultation with the allies – the P5 + 1 and Israel.

The official pointed out that there have been bilateral talks in the past – but that Iran refused to even meet with the P5 +1 during the recent United Nations meetings. He said the Iranians know there will be no agreement unless they give up their nuclear program.

Asked about the impact on Monday's foreign policy debate between President Barack Obama and Republican nominee Mitt Romney, the official said the administration is not happy that the story came out before the debate, but said the American people might be happy to know the administration is willing to explore all possibilities to get Iran to give up its nuclear program.

The Times, citing a senior administration official, said Iranian officials had insisted that the talks wait until after the presidential election so that they would know which president would be negotiating with them. The Times said: "Reports of the agreement have circulated among a small group of diplomats involved with Iran."

But in a statement Saturday evening, National Security Council spokesman Tommy Vietor said the U.S. and Iran had no such agreement:

It's not true that the United States and Iran have agreed to one-on-one talks or any meeting after the American elections. We continue to work with the P-5+1 on a diplomatic solution and have said from the outset that we would be prepared to meet bilaterally. The President has made clear that he will prevent Iran from getting a nuclear weapon, and we will do what we must to achieve that. It has always been our goal for sanctions to pressure Iran to come in line with its obligations. The onus is on the Iranians to do so, otherwise they will continue to face crippling sanctions and increased pressure.

World powers accuse Iran of covertly using its uranium enrichment program to produce nuclear weapons. The Iranians insists the research and development is for projects to generate electricity and produce medical isotopes.

A six-country alliance of Western powers, including the United States, has been attempting to negotiate with the Iranians, with occasional concessions by Iran and assertions that it’s willing to engage with the alliance. Despite the protracted dialogue, diplomats hope that a negotiated settlement can be reached, with international sanctions providing an incentive.

In October 2009, the U.S and the Iranians agreed in Geneva that Iran would send its enriched uranium to Russia for safekeeping, in exchange for an agreement for enough nuclear fuel for its Tehran medical research reactor. However, the deal fell apart when Iran's negotiators returned home. Iranian officials told NBC News that their supreme leader, the Ayatollah Khomeini, told them they had gone beyond their instructions. That experience has made the White House wary of any agreement that is not blessed by the supreme leader, the sole authority over nuclear decisions in Iran.

The sanctions began to bite this summer. Hyperinflation in Iran is pushing up prices daily and the dramatic slide in the value of the rial against the U.S. dollar led to unrest in Tehran earlier this month, when angry currency traders clashed with security forces.

Israel, believed to have the Middle East's only atomic arsenal, sees a nuclear-armed Iran as a threat to its existence and has expressed frustration over the failure of diplomacy and sanctions to rein in Tehran. Western nations fear that a possible strike against Iran's facilities by Israel would lead to wider conflict.